Controlled pulse air filter system

ABSTRACT

An air filtering system and method for self-cleaning the same is provided. The system has a plurality of air filters including a first filter and at least one neighboring filter. A blower fan pulls air through the filters. A plurality of compressed air injectors are provided adjacent the filters including a first injector and at least one neighboring injector. Self-cleaning is achieved while the blower fan is running by preforming several steps including activating the first injector to force compressed air into the first filter and discharge particulate from the first filter followed by deactivating the first injector. The steps further provide reactivating the first injector and simultaneously activating the neighboring injector while the discharged particulate is airborne to provide an air shield about the first filter and force the discharged particulate away from the first filter and the neighboring filter. These steps are repeated for each filter.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional application which claims priority to U.S. patentapplication Ser. No. 13/769,641, filed Feb. 18, 2013, entitled“Controlled Pulse Air Filter System” which claims benefit to provisionalapplication No. 61/702,378, filed on Sep. 18, 2012, entitled “ControlledPulse Air Filter System,”, the entirety of which is hereby incorporatedby reference.

TECHNICAL FIELD

This invention relates generally to air filtering systems and, moreparticularly, to a controlled pulse air filtering system. A method forself-cleaning the filters of such an air filtering system is alsodescribed and claimed herein.

BACKGROUND OF THE INVENTION

Air filtering units are commonly used in manufacturing processes. Onetypical application is to clean the air within a welding station. Aconduit is connected between an opening in the welding station and theair filtering unit. During operation of the air filtering unit, the airwithin the welding station is drawn from the welding station, throughthe conduit and into the filtering unit by a blower fan. A plurality offilters are mounted in the filtering unit and the air from the weldingstation is pulled through the filters. the filters extract theparticulate from the air and then the air is expelled from the filterunit back into the surrounding environment.

Over time, the filters become dirty with the particulate and requirecleaning. There are typically two times when the filters are cleaned.One time is during total shut down and the other during operation. Thelatter is done to extend the period between the cleanings done at totalshutdown. Shutdown, as will be appreciated, effects the normal operationof the manufacturing operations and the longer the period between thetotal shutdowns for cleaning the better.

To clean such air filtering units, air injectors are traditionallypositioned adjacent to each of the filters. The air injectors aresupplied with compressed air. All of the air injectors aresimultaneously actuated forcing compressed air into and through thefilters, from the inside to the outside, for the purpose of dischargingany particulates that have accumulated on the filters. Generally, thecompressed air released from the air injectors and gravity directs thedischarged particulates into a collector unit disposed below thefilters. During total shutdown, a large amount of the particulate thathas accumulated on the filters can be forced out of the filters.However, during cleaning with the unit operational (i.e. when the blowerfan is running), only a small amount of the particulate is dischargedand most is sucked back onto the filters because the filter unit isdrawing air through the filters. The particulate that is discharged fromthe filters is for the most part immediately pulled back onto thefilters.

The controlled pulse of the present invention overcomes this problem ofthe discharged particulate being drawn back onto the filters duringcleaning operations when the filter unit is operational.

SUMMARY OF THE INVENTION

In general terms, this invention provides an improved method forcleaning the filters of an air filtering unit while the unit isoperational. The method of the present invention includes providing aplurality of air filters and providing a plurality of compressed airinjectors adjacent the air filters. During operation of the unit, afirst injector is activated to force compressed air into a first filter.This discharges particulate from the first filter. After activating thefirst injector, the first injector is immediately deactivated andre-activated. When the first injector is re-activated, the injectorsdirectly adjacent the first injector are also activated. This step isperformed while the discharged particulate is airborne to shield thefirst filter and force at least a portion of the discharged particulateaway from the first filter and the adjacent filters. After the firstfilter is cleaned in accordance with this method, the operation isperformed on each of the remaining filters.

According to another aspect of the invention, a self-cleaning airfiltering system is provided. The self-cleaning air filtering systemincludes a programmable logic controller operably connected tocompressed air injectors to actuate the injectors. The programmablelogic controller is programmed with executable instructions defined bythe steps of the inventive method described above. Accordingly, theexecutable instructions of the programmable logic controller includeactivating a first injector to force compressed air into the firstfilter and discharge particulate from the first filter. The firstinjector is deactivated for a short time and then the first injector isreactivated along with injectors directly adjacent the first injector.This is done while the discharged particulate is airborne to provide anair shield about the first filter and force at least a portion of thedischarged particulate away from the first filter.

The programmable logic controller is programmed to repeat the executableinstructions for each of the air filters in the system.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a front cutaway view of the controlled pulse air filter systemof the present invention;

FIG. 2 is a side partial cutaway view of the controlled pulse air filtersystem of the present invention; and

FIG. 3 is a top cutaway view of the controlled pulse airfiltering systemshowing the plurality of compressed air injectors of the presentinvention.

DESCRIPTION OF THE ENABLING EMBODIMENT

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a method for cleaning particulatefrom the filters of an air filtering system is provided.

Referring to FIGS. 1 and 2, the method is performed by initiallyproviding an air filtering system 20. The disclosed air filtering system20 includes a plurality of air filters 22 serviced by a plurality ofcompressed air injectors 24. While the plurality of air filters 22 maybe arranged in a variety of configuration in accordance with theinvention, it is envisioned that the filters 22 may be disposed inside-by-side spaced relationship. Similarly, each filter 22 in theplurality of air filters 22 may take a variety of shapes andconfigurations without departing from the scope of this invention. Forexample, each air filter 22 may include a filter material 26 of anelongated cylindrical shape surrounding a hollow core. The filters 22may be spaced apart from one another by a predetermined distance dextending linearly between the filter material 26 of adjacent filters22. As such, the predetermined distance d may be the smallest distancethat can be measured between adjacent filters 22 arranged inside-by-side spaced relationship.

Still referring to FIGS. 1 and 2, the plurality of air filters 22include a first filter 28 and at least one neighboring filter 30adjacent the first filter 28. Similarly, the plurality of compressed airinjectors 24 include a first injector 32 and at least one neighboringinjector 34 adjacent the first injector 32. It should be appreciatedthat the first injector 32 is disposed adjacent the first filter 28 andthat each neighboring injector 34 is disposed adjacent the correspondingneighboring filter 30. In accordance with this aspect of the invention,there is at least one compressed air injector 24 for each filter 22. Acompressed air supply 36 is provided in fluid communication with thecompressed air injectors 24 to supply the injectors 24 with a source ofcompressed air. It should be appreciated that the present invention isnot limited to a compressed air supply 36 and that other types ofcompressed gas may alternatively be supplied to the injectors 24. Itshould also be appreciated that where the filters 22 have acylindrically shaped filter material 26 defining a hollow core, each ofthe compressed air injectors 24 may be aimed such as to provide a pulseof compressed air into the hollow core of the filters 22. Withoutintending to be bound by the theory, it is believed that the pulse ofcompressed air into the hollow core of the filters 22 dischargesparticulate that has accumulated on the filter material 26 byintroducing a shockwave of air into the filter 22. It is furtherbelieved that this shockwave functions to expand folded pleats of thefilter material 26 thereby releasing dirt that has accumulated on thefilter 22.

The plurality of air filters 22 may be provided within a housing 38. Ablower fan 40 maybe provided in fluid communication with the housing 38to facilitate the flow of air through the filters 22. While the housing38 may take a variety of forms, the housing 38 may be generallyrectangular in shape. The housing 38 may also be provided with acollector unit 42 in fluid communication with the filters 22. During useof the air filtering system 20, the collector unit 42 may collect andtrap particulate disposed within the housing 38. Generally, thecollector unit 42 may take the form of a frustoconcial shape extendingdownwardly from the housing. The collector unit 42, or a trap 44attached thereto, may be removably attached to the housing 38 for easeof cleaning. Together with the collector unit 42, the housing 38 maydefine an inlet 46 for receiving a volume of air to be filtered. Thehousing 38 may further define an outlet 48 for discharging a volume offiltered air after it has passed through the filters 22.

The method includes a series of steps wherein the compressed airinjectors 24 are actuated to deliver a series of controlled pulses ofcompressed air to the plurality of air filters 22. The method includesthe step of activating the first injector 32 for a first time durationto force compressed air into the first filter 28 and dischargeparticulate from the first filter 28. This step is referred to herein asthe activating step. It should be appreciated that during the activatingstep, the first injector 32 is activated while the at least oneneighboring injector 34 remains deactivated. The method proceeds withthe step of deactivating the first injector 32 for a second timeduration. This step is referred to herein as the deactivating step. Thesecond time duration of the deactivating step may be shorter than thefirst time duration of the activating step. Accordingly, the firstinjector 32 may be deactivated for only a brief moment. Morespecifically, the second time duration of the deactivating step is lessthan a time required for the discharged particulate to travel thepredetermined distance d between the first filter 28 and the neighboringfilter 30 or neighboring filters 30. This allows enough time for theparticulate to leave the first filter 28 but does not present enoughtime for the particulate to migrate across the predetermined distance dto become entrained on the at least one neighboring filter 30.

The method further includes the step of reactivating the first injector32 and simultaneously activating the at least one neighboring injector34 for a third time duration. This step is referred to herein as thereactivating step. As the term is used herein, the reactivating stepincludes both the reactivation of the first injector 32 and thesimultaneously activation of the at least one neighboring injector 34.The third time duration of the reactivating step may be longer than thefirst time duration of the activating step. Accordingly, the firstinjector 32 and the at least one neighboring injector 34 providesimultaneous pulses of compressed air while the discharged particulateis airborne and force at least a portion of the discharged particulateaway from the first filter 28 and the at least one neighboring filter30, directing the discharged particulate towards the collector unit 42.Without intending to be bound by the theory, it is believed that thereactivating step provides an air shield about the first filter 28 thatprevents the first filter 28 and the at least one neighboring filter 30from entrapping or re-entrapping the discharged particulate when it isairborne as a result of the activation of the first injector 32 duringthe activation step.

In addition to differences in the time duration between compressed airpulses of the activating and reactivating steps, the pressure of thecompressed air may differ between the activating and reactivating step.For instance, the activating step of activating the first injector 32 toforce compressed air into the first filter 28 and discharge articulatefrom the first filter 28 may further include supplying a first pressurepulse to the first filter 28. The reactivating step of reactivating thefirst injector 32 and activating the at least one neighboring injector34 simultaneously following the deactivation of the first injector 32and while the discharged particulate is airborne may further includesupplying a second pressure pulse simultaneously to the first filter 28and the at least one neighboring filter 30 wherein the first pressurepulse is greater than the second pressure pulse. In other words, thefirst pressure pulse of the activating step may be of a higher orgreater positive pressure than that of the second pressure pulse of thereactivating step.

These method steps may then be repeated for each of the plurality of airfilters 22. Consequently, the filter 22 being designated as the firstfilter 28 will change with each iteration of the method until all of thefilters 22 have been cleaned by the controlled pulses of compressed air.Advantageously, the subject method may be employed during operation ofthe air filtering system 20. As such, the method of delivering thecontrolled pulses of compressed air to the filters 22 may be performedwhile air is being communicated through the filters 22. In other words,the method steps recited above may all be performed while the blower fan40 is running to draw air through the filters 22. Nevertheless, itshould be appreciated that the subject method may be performed while theair filtering system 20 is not in operation.

More particularly, FIG. 3 illustrates an exemplary air filter system 20of the subject invention having a total of twelve filters 22 and twelveinjectors 24 a-1. For a first exemplary iteration of the methoddescribed herein, injector 24 a may be designated as the first injector32 and injectors 24 b, 24 f, and 24 e may be designated as theneighboring injectors 34 observing that injectors 24 b, 24 f, and 24 eare directly adjacent injector 24 a. In accordance with the methoddescribed herein, the first injector 24 a is activated while theneighboring injectors 24 b, 24 f, and 24 e remain deactivated. Next, thefirst injector 24 a is deactivated. Following the deactivation of thefirst injector 24 a, the first injector 24 a is reactivated and, at thesame time, the neighboring injectors 24 b, 24 f, and 24 e are activatedto shield the filters 22 from the discharged particulate as it istravels to the collector unit 42. This cleaning methodology may then berepeated for each of the filters 22 and repeats itself for as long asthe air filter system 20 is in operation.

For instance, the method may continue with a second exemplary iterationwherein injector 24 b is designated as the first injector 32 andinjectors 24 a, 24 f, and 24 c are designated as the neighboringinjectors 34 observing that injectors 24 a, 24 f, and 24 c are directlyadjacent injector 24 b. In accordance with the method, the firstinjector 24 b is activated while the neighboring injectors 24 a, 24 f,and 24 c remain deactivated. Next, the first injector 24 b isdeactivated. Following the deactivation of the first injector 24 b, thefirst injector 24 b is reactivated and, at the same time, theneighboring injectors 24 a, 24 f, and 24 c are activated. It should beappreciated that in the second exemplary iteration, the plurality ofneighboring injectors 34 could be expanded to further include injectors24 e and 24 g.

Similarly, the method may continue with a third exemplary iterationwherein injector 24 f is designated as the first injector 32 andinjectors 24 b, 24 e, 24 j, and 24 g are designated as the neighboringinjectors 34 observing that injectors 24 b, 24 e, 24 j, and 24 g aredirectly adjacent injector 24 f. In accordance with the method, thefirst injector 24 f is activated while the neighboring injectors 24 b,24 e, 24 j, and 24 g remain deactivated. Next, the first injector 24 fis deactivated. Following the deactivation of the first injector 24 f,the first injector 24 f is reactivated and, at the same time, theneighboring injectors 24 b, 24 e, 24 j, and 24 g are activated. Again,it should be appreciated that in the third exemplary iteration, theplurality of neighboring injectors 34 could be expanded to furtherinclude injectors 24 a, 24 i, 24 k and 24 c.

Referring back to FIGS. 1 and 2, a self-cleaning air filtering system 20adapted to perform the method described herein is provided. The airfiltering system 20 has a housing 38 including an inlet 46 and an outlet48. The housing 38 may be divided into several plenums including a firstplenum 50, a second plenum 52, and a third plenum 54 each beingpartially separated from one another by a plurality of dividers 56. Thefirst plenum 50, also referred to as the dirty air plenum, is adjacentthe inlet 46 and receives a volume of air from the inlet 46 to befiltered. As an example, the inlet 46 may be in fluid communication witha welding station. The first plenum 50 houses a plurality of air filters22 including a first filter 28 and at least one neighboring filter 30adjacent the first filter 30. The plurality of air filters 22 may bedisposed in side-by-side spaced relationship and each air filter 22includes a filter material 26 of an elongated cylindrical shapesurrounding a hollow core. The plurality of air filters 22 may bemounted to the divider 56 partially separating the first plenum 50 andthe second plenum 52. Additionally, this divider 56 may include aplurality of holes that are radially aligned with the hollow core ofeach filter 22 through which air may travel from the first plenum 50 tothe second plenum 52.

The second plenum 52, also referred to as the air tank plenum, isdisposed between the first plenum 50 and the third plenum 54. The secondplenum 52 may house a plurality of compressed air injectors 24 adjacentto the air filters 22 including a first air injector 32 adjacent thefirst filter 28 and at least one neighboring injector 34 adjacent eachneighboring filter 30. The air injectors 24 are positioned to forcecompressed air into the hollow core of the air filters 22 and eachinjector 24 may further include a nozzle 58 configured to diffuse theair pulse provided by the injector 24 over a larger area. A compressedair supply 36 is provided in fluid communication with the compressed airinjectors 24 to supply the injectors 24 with compressed air. It shouldbe appreciated that the compressed air supply 36 could be a tank ofcompressed air or an air compressor. Further, the compressed air supply36 may be part of the air filtering system 20, a standalone unit, or acompressed air line common in many factories or plants. As such, thecapacity of the compressed air supply 36 may be limited such that thepressure provided to the injectors 24 may vary depending on thefrequency with which the injectors 24 are activated. The divider 56partially separating the second plenum 52 and the third plenum 54 mayinclude a plurality of venturi openings 60 through which air may travelfrom the second plenum 52 to the third plenum 54.

The third plenum 54, also referred to as the blower plenum, is adjacentthe outlet 48 which discharges the filtered air. The third plenum 54 mayhouse a blower fan 40 for drawing air through the air filtering system20. As a result of the blower fan 40 in combination with the venturiopenings 60, the first plenum 50 and second plenum 52 may operate in anegative pressure environment while the third plenum 54 may operate in apositive pressure environment. The negative pressure environment of thefirst plenum 50 and second plenum 52 facilitates drawing dirty air inthrough inlet 46 and through the filters 22 from outside the filtermaterial 26 to inside the hollow core. The positive pressure environmentof the third plenum 54 facilitates expelling filtered air out throughthe outlet 48. Accordingly, an exemplary flow path of air through theair filtering system 20 is as follows. Air is drawn in through the inlet46 and received in the first plenum 50. The air is pulled through thefilters 22 from outside the filter material 26 and into the hollow coreof the filters 22. The air passes from the hollow core of the filters22, through the holes in the divider 56 separating the first plenum 50and the second plenum 52, and into the second plenum 52. The air thentravel from the second plenum 52 to the third plenum 54 through theventuri openings 60. Once in the third plenum 54, the air is expelledthrough the outlet 48.

A collector unit 42 is disposed in fluid communication with the filters22 for collecting and trapping particulate. More particularly, thecollector unit 42 may be connected to the housing 38 adjacent the firstplenum 50. Both the air pulses from the injectors 24 and gravity mayfacilitate the passage of particulate from the filters 22 to thecollector unit 42. The collector unit 42 may have upwardly sloping sidesor may have a frustoconical shape. A trap 44 may be removably connectedto the collector unit 42 for receiving the particulate. The trap 44 maygenerally be barrel shaped and disposed beneath the collector unit 42.As such, the trap 44 can be disconnected and cleaned. Alternatively, thetrap 44 may be in the form of a tray that may be slid out from thecollector unit 42 and cleaned. The air filtering system 20 may besupported by a frame 62. The frame 62 may be attached to the collectorunit 42 and/or the housing 38.

The air filtering system 20 further includes a programmable logiccontroller 64 electrically connected to the compressed air injectors 24.The programmable logic controller 64 is programmed with executableinstructions including activating the first air injector 32 for a firsttime duration to force compressed air into the first filter 28. Thisdischarges particulate from the first filter 28, rendering it airborneoutside the filter material 26 of the first filter 28 and within thefirst plenum 50. The executable instructions also include deactivatingthe first air injector 32 for a second time duration being shorter thanthe first time duration and reactivating the first air injector 32 andsimultaneously activating the at least one neighboring injector 34 for athird time duration being longer than the first time duration.Accordingly, the first injector 32 is reactivated and the at least oneneighboring injector 34 is simultaneously activated while the dischargedparticulate is airborne to provide an air shield about the first filter28 and force at least a portion of the discharged particulate away fromthe first filter 28 and the at least one neighboring filter 30 andtowards the collector unit 42. The programmable logic controller 64further provides for repeating the executable instructions for each ofthe air filters 22.

As a result of these executable instructions and the method describedabove, a greater amount of the discharged particulate is forced into thecollector unit 42 than would be achieved by traditional online cleaningoperations where all of the injectors 24 are activated at the same timewhile the blower fan 40 is running. Through testing, as much as fivetimes the discharged particulate reached the collector unit 42 whencompared to the traditional online cleaning operation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of theappended claims. These antecedent recitations should be interpreted tocover any combination in which the inventive novelty exercises itsutility. The use of the word “said” in the apparatus claims refers to anantecedent that is a positive recitation meant to be included in thecoverage of the claims whereas the word “the” precedes a word not meantto be included in the coverage of the claims. In addition, the referencenumerals in the claims are merely for convenience and are not to be readin any way as limiting.

What is claimed is:
 1. A self-cleaning air filtering system, comprising;a plurality of air filters including a first filter and at least oneneighboring filter adjacent said first filter, a plurality of compressedair injectors including a first injector and a neighboring injector foreach neighboring filter for forcing compressed air into said airfilters, a programmable logic controller operably connected to saidcompressed air injectors to actuate said compressed air injectors andsaid control unit being programmed with executable instructionsincluding activating said first injector to force compressed air intosaid first filter and discharge particulate from said first filter anddeactivating said first injector and reactivating said first injectorand simultaneously activating said at least one neighboring injectorwhile the discharged particulate is airborne to provide an air shieldabout said first filter and force a portion of the dischargedparticulate away from said first filter and said at least oneneighboring filter.
 2. The system of claim 1, wherein said programmablelogic controller is programmed to repeat said executable instructionsfor each of said air filters in said plurality of air filters.
 3. Thesystem of claim 2, wherein said executable instructions programmed intosaid programmable logic controller include activating said firstinjector for a first time duration and deactivating said first injectorfor a second time duration being shorter than said first time durationand reactivating said first injector and simultaneously activating saidat least one neighboring injector for a third time duration being longerthan said first time duration.
 4. The system of claim 3, wherein saidfirst filter and said at least one neighboring filter are spaced apartby a predetermined distance and said second time duration is less than atime required for the discharged particulate to travel saidpredetermined distance between said first filter and said at least oneneighboring filter.
 5. The system of claim 4, wherein said at least oneneighboring injector includes a plurality of neighboring injectors andsaid executable instructions programmed into said programmable logiccontroller include reactivating said first injector and simultaneouslyactivating all neighboring injectors in said plurality of neighboringinjectors.
 6. The systems of claim 5, further comprising; a housingincluding an inlet for receiving air and an outlet for discharging air,and a blower fan disposed within said housing for communicating air fromsaid inlet through said plurality of air filters to said outlet.
 7. Thesystem of claim 6, wherein said programmable logic controller isprogrammed to perform said executable instructions while said blower fanis communicating air from said inlet through said plurality of airfilters to said outlet.
 8. The system of claim 7, wherein each filter isprovided with one injector adjacent said filter with said first injectorbeing disposed adjacent said first filter and each neighboring injectorbeing disposed adjacent each neighboring filter.
 9. The system of claim8, further comprising; a collector unit in fluid communication with saidplurality of air filters for collecting and trapping particulatedischarged from said plurality of air filters.
 10. The system of claim9, wherein said air filters are disposed in side-by-side spacedrelationship forming a rectangular grid-like arrangement.
 11. The systemof claim 10, further comprising; a compressed air supply in fluidcommunication with said compressed air injectors for supplyingcompressed air to said compressed air injectors.
 12. The system of claim11, wherein said programmable logic controller is electrically connectedto said compressed air injectors and controls actuation of saidcompressed air injectors by sending electronic signals to saidcompressed air injectors.
 13. The system of claim 12, wherein each ofsaid air filters are formed of at least a filter material having anelongated cylindrical shape surrounding a hollow core.
 14. The system ofclaim 13, wherein said predetermined distance is the shortest distancebetween said first filter and said at least one neighboring filter andextends linearly from said filter material of said first filter to saidfilter material of said at least one neighboring filter.